It looks like GHash.io's litecoind (or equivalent) was desynced from the rest of the Litecoin network for a few hours. GHash.io was continually trying to solve block #531801 because, for whatever reason, it had not received the dozens of blocks which had been found by the network since that one.

The situation appears to have been resolved now, since a few minutes ago Ghash.io found block #531891.